1. Field of the Invention
The present invention relates to charge-coupled devices, and more particularly to charge-coupled linear image devices which accomodates a greater number of image sensor elements in a sensing area.
2. Description of the Prior Art
Charge-coupled linear image sensing devices are such as described in an article titled "Interlacing in Charge-Coupled Imaging Devices" by Carlo H. Sequin, IEEE Transactions on Electron Devices, Vol. ED-20, No. 6(June, 1973), pp. 535-541, and in a catalog for "500-Element Charge Coupled Linear Image Sensor", published by Fairchild Camera and Instrument Corporation. In these conventional devices, an image sensor array includes a number of image sensor elements arranged in one-dimensional fashion and is installed separately from charge transfer arrays. The charge transfer arrays are usually two in number and disposed on both sides of the image sensor array for transferring the charge developed in the image sensor array in response to incident light rays.
In these devices, however, the drive frequency must be as high as several megahertz to address a substantial number of image sensor elements in the sensing area. Furthermore, the charge transfer efficiency from one stage to another in a charge-coupled device is not 100%, the overall charge-transfer efficiency decreasing as the number of charge-transfer stages increases. For these reasons, it has thus far been nearly impossible to accomodate a desired number of image sensor elements in the sensing area.